High dielectric constant composite material and multilayer wiring board using the same

ABSTRACT

A high dielectric composite material obtained by subjecting submicron particles of an inorganic filler containing a metal as its essential component to an insulating treatment such as a chemical treatment, further subjecting to a surface treatment for improving their compatibility with organic resins, and then dispersing in an organic resin, has a dielectric constant of 15 or above, with its dielectric loss tangent in the frequency region of from 100 MHz to 80 GHz being 0.1 or less, and can therefore be used effectively for multilayer wiring boards and module substrates.

BACKGROUND OF THE INVENTION

The present invention relates to a high dielectric constant materialused for multilayer wiring boards having a built-in passive elementcapacitor, and a multilayer wiring board and a module substrate usingthe said material.

In order to realize high-density surface packaging, many studies havebeen made for reducing the size of via holes, narrowing down wiringpitch, establishing the build-up system, etc., in the manufacture of thesubstrates. Efforts have also been made for miniaturization of ICpackages, multiplication of pins, miniaturization and surface packagingof the passive parts such as condensers and resistors. On the otherhand, with the progress of miniaturization of the passive elements,there arose a problem in that their handling became more difficult inthe manufacture and packaging thereof, and the limitation of theconventional technology in this line has become apparent. As a solutionto this problem, it has been proposed to form the passive elementsdirectly on the surface or in the inside of a printed wiring board. Thismakes it unnecessary to mount the passive element chip parts on theprinted wiring board, conducing to realize high-density packaging and anenhancement of reliability. The conventional coating and sinteringtechniques using a paste of a metal or an insulator, such as practicedwith the ceramic substrates, can not be directly applied to the othertypes of substrates, especially organic substrates which are low in heatresistance.

As means for forming the passive elements such as mentioned above on anorganic substrate, there have already been proposed the methodscomprising coating the substrate with a mixture of an organic polymerand a high dielectric filler (P. Chanel et al, 46th Electric Componentsand Technology Conference, pp. 125–132, 1996; Y. Rao et al, 2000Electric Components and Technology Conference, pp. 615–618, 2000), atechnique for elevating the packing rate of an inorganic filler such asbarium titanate (JP-A-6-172618), and a method using ECR-CVD (electroniccycloton resonance chemical vapor deposition) which is capable of filmforming at low temperature (T. Matsui et al, Circuit Technology, Vol. 9,pp. 497–502, 1994).

It is necessary to raise the filler loading for elevating the dielectricconstant of the filler applied as a composite with an organic resin.High loading of an inorganic filler in a resin, however, tends to causeformation of voids when the resin is cured, due to bad compatibility ofinorganic fillers with resins. Further, because of low interfacialadhesion between inorganic filler and resin, there tends to take placeseparation at the interface. Therefore, use of a resin composite withhigh inorganic filler loading as an insulating material raises theconcern that reliability be lowered in relation to dielectric strengthor leakage current.

Also, the method using ECR-CVD has problems in that a specific apparatusmust be used, that it is impossible to form the dielectric films at lowcost by a batch process, and that it is difficult to form a dielectricfilm having a complicate configuration.

On the other hand, as means for increasing the dielectric constant, amethod is suggested in which a metal power having an average particlesize of not less than several ten μm, which is the standard size ofmetal powders, is filled in an organic resin. Although such a compositematerial shows a satisfactory dielectric constant of not less thanseveral ten, it suffers a dielectric loss tangent of not smaller than0.1 due to skin effect, and more seriously, such an organic resin/metalcomposite is very low in insulating performance. Further, miscibility oforganic resin with metal is bad like inorganic materials.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a high dielectricconstant composite material having a volume resistivity of 10⁹ Ω orhigher and also maintaining a high dielectric constant of 15 or aboveand a low dielectric loss tangent of 0.1 or below even in the highfrequency region of several tens GHz order, and a multilayer wiringboard using such a composite material.

Another object of the present invention is to provide a high dielectricconstant composite material compounded with an organic resin capable offorming a passive element directly on a surface or interior of a printedwiring board, and good in processability, and a multilayer printedwiring board using the same.

The present invention provides a high dielectric constant compositematerial having a dielectric constant of 15 or above, comprising anorganic resin and, dispersed therein, an inorganic filler containing ametal powder as an essential component.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjugation with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the particles of metal powder after theinsulation treatment in the first and second embodiments of the presentinvention.

FIG. 2 is a sectional view of the particles of metal powder after thesurface treatment in the first and second embodiments of the presentinvention.

FIG. 3 is a sectional view of the high dielectric constant compositematerial in the first and second embodiments of the present invention.

FIG. 4 is a cross-sectional view of the agglomerated metal powder afterthe insulation treatment in the fourth embodiment of the presentinvention.

FIG. 5 is a cross-sectional view of the agglomerated metal powder afterthe surface treatment in the fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of the high dielectric constantcomposite material in the fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view of the agglomerated metal powder afterplating in the fifth embodiment of the present invention.

FIG. 8 is a cross-sectional view of the agglomerated metal powder afterthe insulation treatment in the fifth embodiment of the presentinvention.

FIG. 9 is a cross-sectional view of the agglomerated metal powder afterthe surface treatment in the fifth embodiment of the present invention.

FIG. 10 is a cross-sectional view of the high dielectric constantcomposite material in the fifth embodiment of the present invention.

FIG. 11 is a cross-sectional view of the agglomerated metal powder afterthe insulation treatment in the sixth embodiment of the presentinvention.

FIG. 12 is a cross-sectional view of the metal/inorganic mattercomposite powder after the surface treatment in the sixth embodiment ofthe present invention.

FIG. 13 is a cross-sectional view of the high dielectric constantcomposite material in the sixth embodiment of the present invention.

FIG. 14 is a sectional view of the metal/inorganic resin compositepowder in the seventh and eighth embodiments of the present invention.

FIG. 15 is a sectional view of the metal/inorganic matter compositepowder after the insulation treatment in the seventh and eighthembodiments of the present invention.

FIG. 16 is a sectional view of the metal/inorganic matter compositepowder after the surface treatment in the seventh and eighth embodimentsof the present invention.

FIG. 17 is a sectional view of the high dielectric composite material inthe seventh and eighth embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In order to attain the above object, it is essential to use metal powderwhich suffers no energy loss due to skin effect even at a high frequencyof several tens GHz order, and it is important therefor that the size ofthe metal powder is submicron, and that insulation is secured for everyparticle of metal powder. There are available various methods forinsulation treatment of the individual particles of metal powder, but achemical treatment with an inorganic salt such as phosphates orchromates is most effective. This is for the reason that an insulationlayer of an inorganic salt is formed on the particle surfaces of metalpowder by this treatment. This insulating film has higher anti-heat andanti-moisture reliability than other types of insulating film.

For raising dielectric constant of an organic resin-based compositematerial, it is imperative to increase loading of said metal powder inthe organic resin, for which it is essential to improve compatibilitybetween said metal powder and organic resin. An effective means forattaining this is the coupling treatment which is capable of forming achemical bond between the metal surface and the insulation layer thereonas well as a chemical bond with the organic resin, too.

The characteristic features of the present invention are describedbelow.

The first feature of the present invention is that a high dielectricconstant composite material having a dielectric constant of 15 or above,comprising an organic resin and, dispersed therein, an inorganic fillercontaining a metal powder as its essential component, is provided.

The second feature of the present invention is that this high dielectricconstant material suffers a dielectric loss tangent of only 0.1 or lessin the frequency region of from 100 MHz to 80 GHz.

It was further disclosed by the present invention that for restrictingthe dielectric loss tangent to 0.1 or less in the frequency region offrom 100 MHz to 80 GHz, it is necessary that every component in theinorganic filler containing a metal powder as essential component has anaverage particle size of 5 μm or less. Here, an inorganic fillercomprising a metal oxide may be added for preventing sedimentation ofthe metal powder in the resin varnish. It is also effective to use acomposite material in which the particle size of the metal powder wasrestricted to submicron by complexing of an inorganic filler comprisinga metal powder and the one comprising a material other than metalpowder.

It is an important technique for minimizing the dielectric loss tangentin the high frequency region and securing the required insulatingproperties to use an inorganic filler having as essential component ametal powder which has been surface treated to form an oxide film orwhich has been subjected to an insulation treatment by a suitable methodsuch as coating with an organic resin. Implementation of this techniqueis the fourth feature of the present invention. It is even moreeffective to jointly use a metal oxide for satisfying both requirementsfor high dielectric constant and required insulating performance. Forthis, a method may be employed in which the metal powder is coated witha metal oxide.

By virtue of this insulating treatment or coating with a metal oxide,the high dielectric composite material of the present invention has avolume resistivitiy of 10⁹ Ω cm or above and is suited for use assubstrates for electronic devices.

The inorganic filler containing a metal powder as its essentialcomponent may include agglomerates thereof having an average particlesize of 5 μm or less.

The metals usable as metal powder in the present invention include theelements of Groups 1B, 2B, 3B, 4B, 5B, 6B, 7B, 8, 2A, 3A, 4A and 5A(excluding boron, carbon, nitrogen, phosphorus and arsenic) of thePeriodic Table and their alloys, for instance, Al, Mn, Si, Mg, Cr, Ni,Nb, Mo, Cu, Fe, W, Zn, Sn, Pb, Ag, Ti, Zr, Ta, Pt, Sb, and their alloys.

The metal powder may have a metallic covering such as electric platedfilm the surface thereof with a thickness of 1000 to 1 nm using at leastone metal selected from Cr, Cd, Zn, Mn and Fe.

The organic resins applicable in the present invention includethermosetting resins such as epoxy resins, phenol resins, bismaleimideresins and cyanate resins, thermoplastic resins such as polyimideresins, polyphenylene oxide and polyphenylene sulfide, and mixturesthereof. If desired, such an organic resin may be dispersed in a solventsuch as methyl ethyl ketone, isopropyl alcohol or methyl Cellosolve toform a paste or a dispersion, which is subjected to screen printing orspin coating to form a high dielectric constant layer.

As another feature of the present invention, a composite materialcomprising an organic resin and, dispersed therein, an inorganic fillerhaving as essential component a metal powder which has been subjected toa surface insulation treatment and coupling treatment (or surfacetreatment) is used for the capacitor in a multilayer wiring board inwhich a capacitor having a dielectric layer interposed between theelectrodes is formed in the circuit, to thereby provide a multilayerwiring board having a built-in condenser with a large electricalcapacitance.

As still another feature of the present invention, a composite materialcomprising an organic resin and, dispersed therein, an inorganic fillerhaving as essential component a metal powder subjected to insulation andcoupling treatments on the surface is used for the capacitor in a modulesubstrate in which a capacitor having a dielectric layer interposedbetween the electrodes is formed in the circuit, to provide a modulesubstrate having a built-in condenser with a large electricalcapacitance.

The present inventors found that for obtaining a composite materialcontaining an organic resin and having a dielectric constant of 25 orgreater and a dielectric loss tangent of 0.1 or less even at a frequencyof several tens GHz order, it is expedient to apply a chemicalinsulation treatment with an inorganic salt and to fill in the organicresin a metal powder of a submicron size which has been subjected to acoupling treatment.

Use of a metal powder of a submicron size is intended to minimize thedielectric loss tangent due to skin effect at a frequency of the severaltens GHz order. It is for the same reason that securing of insulatingperformance of the individual particles of metal powder by the chemicaltreatment using an inorganic salt is important. The coupling treatmenton the metal powder which has been subjected to an insulation treatmentis conducted as it is imperative to improve compatibility with the resinused. This treatment is schemed not only to increase metal powderloading in the resin but also to improve workability of the mixture andinhibit sedimentation of the metal powder.

As a result of the metal powder insulation treatment, the produced highdielectric constant composite material incorporating an organic matterhas a volume resistivity of 10⁹ Ω cm or higher.

The effect of the present invention is described below more definitelywith reference to the Examples thereof.

EXAMPLE 1

A process for producing a high dielectric constant composite materialaccording to the first embodiment of the present invention is explainedbelow. In this Example, EP828 (produced by Yuka Shell Epoxy Co., Ltd.)was used as epoxy resin, m-phenylenediamine (produced by Wako PureChemical Industries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN(produced by Shikoku Chemicals Corp.) as curing accelerator. Iron powderhaving an average particle size of 0.5 μm was used as a startingmaterial for the high dielectric constant composite material. For theinsulation of iron powder, a phosphate-based chemical treating solutioncontaining 0.4 mol/l of benzotriazole as rust inhibitor and 0.1% byweight of EF104 (produced by Tohchem Products Corp.) as surfactant wasused. S510 (produced by Chisso Corp.) was used as surface treatingsolution for the insulated iron powder.

-   (1) To 1 kg of iron powder having an average particle size of 0.5    μm, 200 ml of the insulating treatment solution was added and the    mixture was stirred by a V mixer for 30 minutes, followed by heat    treatment at 180° C. for 60 minutes. A sectional view of the iron    powder particles after the insulation treatment is shown in FIG. 1.    As seen from FIG. 1, the surface of iron powder 1 is coated with an    insulating film 2 after the insulation treatment.-   (2) The iron powder which has undergone the insulation treatment    of (1) above was then subjected to a surface treatment with an S510    solution diluted to 1 wt % concentration with a water/methanol mixed    solvent, under the conditions of 150° C. and one hour. A sectional    view of the iron powder after the surface treatment is shown in    FIG. 2. It will be seen that after the surface treatment, the    insulating film 2 around iron powder 1 is further coated with a    surface treatment film 3.-   (3) The iron powder subjected to the surface treatment in (2) above    was added to a liquid epoxy resin EP828 in such an amount that would    make the iron powder 50% by volume, and the mixture was kneaded by a    three-roll mill. To the kneaded mixture, m-phenylenediamine was    added in an amount making it equivalent to the epoxy resin in    relation to the curing reaction, followed by further addition of    2E4MZ-CN in an amount of 0.5 part by weight based on the epoxy    resin, and the mixture was kneaded by a three-roll mill.-   (4) The mixture obtained in (3) was heated and cured at 80° C. for 4    hours and then at 180° C. for 4 hours to obtain a high dielectric    constant composite material of the present invention. A sectional    view of this high dielectric constant composite material is shown in    FIG. 3. The high dielectric constant composite material of this    Example is of a structure in which an inorganic filler comprising    metal powder 1 having its surface coated with an insulation layer 2,    said insulation layer 2 being in turn coated with a surface    treatment layer 3, is dispersed in an organic resin 4.

The dielectric constant and dielectric loss tangent of the highdielectric constant composite material of this Example of the presentinvention are explained below. For the measurement in the frequencyregion of 100 MHz to 80 GHz, there were used test pieces obtained fromthe above high dielectric constant composite material worked into atoroidal shape measuring 7 –0.05 mm in external diameter, 3.04+0.06 mmin inner diameter and 2 mm or 4 mm in thickness. For determining thedielectric constant and dielectric loss tangent of the sample by adetermination system comprising a network analyzer (HP 8720C) andcoaxial air line, calibration was made so that the dielectric constantof the free space would become 1, then the sample was inserted in thecoaxial air line and determination was made using two ports. For themeasurement in the frequency region of 5 GHz to 10 GHz, there were usedtest pieces obtained from the high dielectric constant compositematerial worked into a square pillar of 1 mm×1 mm×100 mm, and for themeasurement in the frequency region of 20 GHz to 40 GHz, there were usedtest pieces of film-form test pieces with 100 μm thick. The measurementwas carried out by a cavity resonance method using 8722 ES NetworkAnalizzer manufactured by Agilent Technology Co.

For determination of volume resistivity of the said high dielectriccomposite material, the electrodes having a main electrode externaldiameter of 50 mm, a guard electrode inner diameter of 52 mm, itsexternal diameter of 80 mm and an opposite electrode external diameterof 80 mm were formed on a resin plate made of the said high dielectriccomposite material, and volume resistivity was determined by an LICmeter (HP4248A) at a frequency of 100 kHz. The results are shown inTable 1.

TABLE 1 High di- electric Dielectric Dielectric Volume constant SizeInsulation Surface constant loss resistivity material (μm) treatmenttreatment (0.1–40 GHz) tangent (Ω cm) Example 1 Iron 0.5 ConductedConducted 90–60  0.1–0.04 1 × 10¹⁴ Example 2 Zinc 0.5 ConductedConducted 90–70 0.08–0.04 5 × 10¹³ Example 3 Zinc 3 Conducted Conducted60–30  0.1–0.05 3 × 10¹³ Example 4 Zinc 0.1 Conducted Conducted 40–15 0.1–0.07 6 × 10¹³ (agglo- (5) merate) Example 5 Copper (Cr 1 ConductedConducted 90–70 0.08–0.05 1 × 10¹⁴ plating (0.01) thickness) Example 6Cr—A1₂O₃ 1, 0.1 Conducted Conducted 80–40 0.08–0.04 2 × 10¹⁴ Example 7Fe—A1₂O₃ 0.2 Conducted Conducted 70–30 0.08–0.03 3 × 10¹⁴ Example 8Fe—BaTiO₃ 0.2 Conducted Conducted 75–30  0.1–0.05 2 × 10¹⁴ High di-electric Dielectric Dielectric Volume constant Size Insulation Surfaceconstant loss resistivity material (μm) treatment treatment (0.1–5 GHz)tangent (Ω cm) Comp. Iron 5 Conducted Conducted 55–15 0.8–0.08 2 × 10¹³Example 1 Comp. Zinc 0.5 Not Conducted 90–30 0.8–0.1 5 × 10³ Example 2Conducted Comp. Zinc 20 Conducted Conducted 20–13 0.5–0.2 1 × 10¹³Example 3 Comp. Zinc 0.1 Conducted Conducted 20–12 0.5–0.1 2 × 10¹³Example 4 (agglo- (50) merate) Comp. Copper 1 Not Conducted 80–300.8–0.1 1 × 10⁴ Example 5 (Cr plating (0.01) Conducted thickness) Comp.Cr—A1₂O₃ 1, 0.1 Conducted Not — — — Example 6 Conducted Comp. Fe—A1₂O₃10 Conducted Conducted 65–20 0.8–0.15 5 × 10¹³ Example 7 Comp. Fe—BaTiO₃0.2 Not Conducted 75–30 0.7–0.1 1 × 10⁵ Example 8 Conducted Note) — :impossible to make test pieces

EXAMPLE 2

A process for producing the high dielectric composite material accordingto the second embodiment of the present invention is explained below. Inthis Example, EP1001 (produced by Yuka Shell Epoxy Co., Ltd.) was usedas epoxy resin, dicyandiamide (produced by Wako Pure ChemicalIndustries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN (produced byShikoku Chemicals Corp.) as curing accelerator. Zinc powder having asaverage particle size of 0.5 μm was used as high dielectric constantmaterial. For the insulation of zinc powder, a phosphate-based chemicaltreating solution comprising 0.4 mol/l of benzotriazole as rustinhibitor and 0.1% by weight of EF104 (produced by Tohchem ProductsCorp.) as surfactant was used. S510 (produced by Chisso Corp.) was usedas surface treating solution for iron powder after the insulationtreatment.

-   (1) To 1 kg of zinc powder having an average particle size of 0.5    μm, 200 ml of the insulation treating solution was added and the    mixture was stirred by a V mixer for 30 minutes and then heated at    180° C. for 60 minutes. A sectional view of the insulated zinc    powder is shown in FIG. 1.-   (2) The zinc powder after the insulation treatment of (1) was    subjected to a surface treatment using an S510 solution diluted to    1% by weight with a water/ethanol mixed solvent, under the    conditions of 150° C. and one hour. A sectional view of the    surface-treated zinc powder is shown in FIG. 2.-   (3) An epoxy resin EP1001 was dissolved in methyl ethyl ketone to a    concentration of 70% by weight.-   (4) To the methyl ethyl ketone solution of the epoxy resin EP1001    prepared in (3), the zinc powder subjected to the surface treatment    of (2) was added in such an amount that it would hold 50% by volume    after curing of the resin, and the mixture was kneaded by a    three-roll mill. To this mixture, dicyandiamide was added in an    amount of 2.5 parts by weight per 100 parts by weight of epoxy    resin, followed by further addition of Curesol CN in an amount of    0.1 part by weight per 100 parts by weight of epoxy resin, and the    mixture was kneaded by a three-roll mill.-   (5) The resulting mixture was desolvated at 100° C. and then heated    and cured at 180° C. for 90 minutes to obtain a high dielectric    constant composite material of the present invention. A sectional    view of the obtained high dielectric constant composite material is    shown in FIG. 3.

The dielectric constant, dielectric loss tangent and volume resistivityof this high dielectric constant composite material were determined inthe same way as in Example 1. The results are shown in Table 1.

EXAMPLE 3

A process for producing the high dielectric constant composite materialaccording to the third embodiment of the present invention is explainedbelow. In this Example, EP806 (produced by Yuka Shell Epoxy Co., Ltd.)was used as epoxy resin, m-phenylenediamine (produced by Wako PureChemical Industries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN(produced by Shikoku Chemicals Corp.) as curing accelerator. A zincpowder having an average particle size of 3 μm was used as a startingmaterial for the high dielectric constant composite material. For theinsulation of the zinc powder, a phosphate-based chemical treatingsolution containing 0.4 mol/l. of benzotriazole as rust inhibitor and0.1% by weight of EF104 (produced by Tohchem Products Corp.) as asurfactant was used. S510 (produced by Chisso Corp.) was used as asurface treating solution for the insulated zinc powder.

-   (1) To 1 kg of zinc powder having an average particle size of 3 μm,    200 ml of the insulating treatment solution was added and the    mixture was stirred by a V mixer for 30 minutes, followed by heat    treatment at 180° C. for 60 minutes. A cross-sectional view of the    zinc powder after the insulation treatment is shown in FIG. 1.-   (2) The zinc powder undergone the insulation treatment in above (1)    was then subjected to a surface treatment using an S510 solution    diluted to 1 wt % concentration with a water/methanol mixed solvent    under the conditions of 150° C. for 1 hour. A cross-sectional view    of the zinc powder after surface treatment is shown in FIG. 2.-   (3) The zinc powder subjected to the surface treatment in above (2)    was added to a liquid epoxy resin EP806 in an amount so as to make    the zinc powder 50% by volume, followed by kneading by a three-roll    mill. To the resulting mixture, m-phenylenediamine was added in an    amount equivalent weight to the epoxy resin in relation to the    curing reaction, followed by further addition of 2E4MZ-CN in an    amount of 0.5 part by weight based on the weight of the epoxy resin.    The resulting mixture was kneaded by a three-roll mill.-   (4) The mixture obtained in above (3) was heated and cured at 80° C.    for 4 hours and at 180° C. for 4 hours to obtain a high dielectric    constant composite material of the present invention. A    cross-sectional view of the high dielectric constant composite    material is shown in FIG. 3.

The dielectric constant, dielectric loss tangent and volume resistivityof the high dielectric constant composite material were measured in thesame manner as in Example 1. The results are shown in Table 1.

EXAMPLE 4

A process for producing the high dielectric constant composite materialaccording to the fourth embodiment of the present invention is explainedbelow. In this Example, EP1001 (produced by Yuka Shell Epoxy Co., Ltd.)was used as epoxy resin, dicyandiamide (produced by Wako Pure ChemicalIndustries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN (produced byShikoku Chemicals Corp.) as curing accelerator. A zinc powder having anaverage particle size of 0.1 μm ground by using a ball mill was used asa starting material for the high dielectric constant composite material.Since the zinc powder was agglomerated, it was sieved with a sievehaving an opening of 5 μm so as to pass the agglomerated zinc powderhaving a maximum particle size of 5 μm or less. For the insulation ofthe zinc powder, a phosphate-based chemical treating solution containing0.4 mol/l. of benzotriazole as rust inhibitor and 0.1% by weight ofEF104 (produced by Tohchem Products Corp.) as a surfactant was used.S510 (produced by Chisso Corp.) was used as a surface treating solutionfor the insulated zinc powder.

-   (1) To 1 kg of agglomerated zinc powder having a maximum particle    size of 5 μm, 200 ml of the insulating treatment solution was added    and the mixture was stirred by a V mixer for 30 minutes, followed by    heat treatment at 180° C. for 60 minutes. A cross-sectional view of    the zinc powder after the insulation treatment is shown in FIG. 4.-   (2) The agglomerated zinc powder undergone the insulation treatment    in above (1) was then subjected to a surface treatment using an S510    solution diluted to 1 wt % concentration with a water/methanol mixed    solvent under the conditions of 150° C. for 1 hour. A    cross-sectional view of the zinc powder after surface treatment is    shown in FIG. 5.-   (3) Epoxy resin EP1001 was dissolved in methyl ethyl ketone so as to    make the concentration 70% by weight.-   (4) The agglomerated zinc powder subjected to the surface treatment    in above (2) was added to the epoxy resin EP1001 dissolved in methyl    ethyl ketone in above (3) in an amount so as to make the zinc powder    50% by volume after resin curing, followed by kneading by a    three-roll mill. To the resulting mixture, dicyandiamide was added    in an amount of 2.5 parts by weight per 100 parts by weight of the    epoxy resin, followed by further addition of Curesol CN in an amount    of 0.1 part by weight based on 100 parts by weight of the epoxy    resin. The resulting mixture was kneaded by a three-roll mill.-   (5) The mixture obtained in above (4) was subjected to removal of    the solvent at 100° C., and heated and cured at 180° C. for 90    minutes to obtain a high dielectric constant composite material of    the present invention. A cross-sectional view of the high dielectric    constant composite material is shown in FIG. 6.

The dielectric constant, dielectric loss tangent and volume resistivityof the high dielectric constant composite material were measured in thesame manner as in Example 1. The results are shown in Table 1.

EXAMPLE 5

A process for producing the high dielectric constant composite materialaccording to the fifth embodiment of the present invention is explainedbelow. In this Example, EP806 (produced by Yuka Shell Epoxy Co., Ltd.)was used as epoxy resin, m-phenylenediamine (produced by Wako PureChemical Industries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN(produced by Shikoku Chemicals Corp.) as curing accelerator. A copperpowder having an average particle size of 1 μm was used as a startingmaterial for the high dielectric constant composite material. For theinsulation of the chromium plated zinc powder, a phosphate-basedchemical treating solution containing 0.4 mol/l. of benzotriazole asrust inhibitor and 0.1% by weight of EF104 (produced by Tohchem ProductsCorp.) as a surfactant was used. S510 (produced by Chisso Corp.) wasused as a surface treating solution for the insulated copper powder.

-   (1) Chromium plating on the surface of copper powder was conducted    by electric plating using a rotating horizontal barrel apparatus.    Average plating layer thickness was 10 nm. A cross-sectional view of    the metal powder after plating 7 is shown in FIG. 7.-   (2) To 1 kg of chromium plated copper powder having an average    particle size of 1 μm obtained in above (1), 200 ml of the    insulating treatment solution was added and the mixture was stirred    by a V mixer for 30 minutes, followed by heat treatment at 180° C.    for 60 minutes. A cross-sectional view of the metal powder after the    insulation treatment is shown in FIG. 8.-   (3) The metal powder undergone the insulation treatment in above (2)    was then subjected to a surface treatment using an S510 solution    diluted to 1 wt % concentration with a water/methanol mixed solvent    under the conditions of 150° C. for 1 hour. A cross-sectional view    of the metal powder after surface treatment is shown in FIG. 9.-   (4) The metal powder subjected to the surface treatment in above (3)    was added to the liquid epoxy resin EP806 in an amount so as to make    the metal powder 50% by volume, followed by kneading by a three-roll    mill. To the resulting mixture, m-phenylenediamine was added in an    amount equivalent weight to the epoxy resin in relation to the    curing reaction, followed by further addition of Curesol CN in an    amount of 0.5 part by weight based on 100 parts by weight of the    epoxy resin. The resulting mixture was kneaded by a three-roll mill.-   (5) The mixture obtained in above (4) was heated and cured at 80° C.    for 4 hours and at 180° C. for 4 hours to obtain a high dielectric    constant composite material of the present invention. A    cross-sectional view of the high dielectric constant composite    material is shown in FIG. 10.

The dielectric constant, dielectric loss tangent and volume resistivityof the high dielectric constant composite material were measured in thesame manner as in Example 1. The results are shown in Table 1.

EXAMPLE 6

A process for producing the high dielectric constant composite materialaccording to the sixth embodiment of the present invention is explainedbelow. In this Example, EP806 (produced by Yuka Shell Epoxy Co., Ltd.)was used as epoxy resin, m-phenylenediamine (produced by Wako PureChemical Industries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN(produced by Shikoku Chemicals Corp.) as curing accelerator. A chromiumpowder having an average particle size of 1 μm and an Al₂O₃ powderhaving an average particle size of 0.1 μm were used as a startingmaterial for the high dielectric constant composite material. For theinsulation of the chromium powder, a phosphate-based chemical treatingsolution containing 0.4 mol/l. of benzotriazole as rust inhibitor and0.1% by weight of EF104 (produced by Tohchem Products Corp.) as asurfactant was used. S510 (produced by Chisso Corp.) was used as asurface treating solution for the insulated chromium powder and Al₂O₃powder.

-   (1) To 1 kg of chromium powder having an average particle size of 1    μm, 200 ml of the insulating treatment solution was added and the    mixture was stirred by a V mixer for 30 minutes, followed by heat    treatment at 180° C. for 60 minutes. A cross-sectional view of the    chromium powder after the insulation treatment is shown in FIG. 11.-   (2) The chromium powder undergone the insulation treatment in    above (1) and the Al₂O₃ power were then subjected to a surface    treatment using an S510 solution diluted to 1 wt % concentration    with a water/methanol mixed solvent under the conditions of 150° C.    for 1 hour. A cross-sectional view of the chromium powder and Al₂O₃    power after surface treatment is shown in FIG. 12.-   (3) The chromium powder and Al₂O₃ powder (3:1 by volume ratio)    subjected to the surface treatment in above (2) was added to the    liquid epoxy resin EP806 in an amount so as to make the metal powder    60% by volume, followed by kneading by a three-roll mill. To the    resulting mixture, m-phenylenediamine was added in an amount    equivalent weight to the epoxy resin in relation to the curing    reaction, followed by further addition of 2E4MZ-CN in an amount of    0.5 part by weight based on 100 parts by weight of the epoxy resin.    The resulting mixture was kneaded by a three-roll mill.-   (4) The mixture obtained in above (3) was heated and cured at 80° C.    for 4 hours and at 180° C. for 4 hours to obtain a high dielectric    constant composite material of the present invention. A    cross-sectional view of the high dielectric constant composite    material is shown in FIG. 13.

The dielectric constant, dielectric loss tangent and volume resistivityof the high dielectric constant composite material were measured in thesame manner as in Example 1. The results are shown in Table 1.

EXAMPLE 7

A process for producing the high dielectric constant composite materialaccording to the seventh embodiment of the present invention isdescribed. In this Example, ESCN190-2 (produced by Sumitomo ChemicalCo., Ltd.) was used as epoxy resin, H900 (produced by Tohto Kasei Co.,Ltd.) as epoxy resin curing agent, and TPP (produced Hokko Chemical Co.,Ltd.) as curing accelerator. A flat Fe/Al₂O₃ composite powder mixed atthe nanometer level was used as high dielectric constant material. Theaverage size of the minor axis of this composite powder was 0.2 μm, andthe Fe to Al₂O₃ volume ratio was 7:3. A sectional view of the Fe/Al₂O₃composite powder used is shown in FIG. 14. As is seen from FIG. 14, themetal/inorganic matter composite powder according to the instant Exampleof the present invention has a structure in which the metal powderparticles 1 are integrated with the inorganic matter 5. Aphosphate-based chemical treating solution comprising 0.4 mol/l ofbenzotriazole as rust inhibitor and 0.1% by weight of EF104 (produced byTohchem Products Corp.) as surfactant was used for the insulation of theFe/Al₂O₃ composite powder. S510 (produced by Chisso Corp.) was used asthe surface treating solution for the iron powder after the insulationtreatment.

-   (1) To 1 kg of the Fe/Al₂O₃ composite powder, 200 ml of the    insulation treating solution was added, and the mixture was stirred    by a V mixer for 30 minutes and then heated at 180° C. for 60    minutes. A sectional view of the Fe/Al₂O₃ composite powder after the    insulation treatment is shown in FIG. 15. As is seen from FIG. 15,    this composite powder is of a structure in which the surface of each    composite powder particle 6 is coated with an insulating film 2.-   (2) The Fe/Al₂O₃ composite powder which had gone through the    insulation treatment of (1) was subjected to a surface treatment    using an S510 solution diluted to a concentration of 1% by weight    with a water/ethanol mixed solvent, under the conditions of 150° C.    and one hour. A sectional view of the Fe/Al₂O₃ composite powder    after the surface treatment is shown in FIG. 16. In this composite    powder, as is seen from FIG. 16, the surface of the insulating film    2 is further coated with a surface film 3.-   (3) An epoxy resin ESCN190-2 and a curing agent H100 were dissolved    in methyl ethyl ketone, each to a concentration of 70% by weight.-   (4) To the methyl ethyl ketone solution of the epoxy resin ESCN190-2    prepared in (3), the Fe/Al₂O₃ composite powder which had undergone    the surface treatment of (2) was added to have a concentration of    50% by volume after curing of the resin, and the mixture was kneaded    by a three-roll mill. To this mixture, H100 was added in an amount    making it equivalent to the epoxy resin in relation to the curing    reaction, followed by further addition of TPP in an amount of 0.4    part by weight per 100 parts by weight of the epoxy resin, and the    mixture was kneaded by a three-roll mill.-   (5) The mixture prepared in (4) was desolvated at 90° C. and then    heated and cured at 180° C. for 6 hours to obtain a high dielectric    constant composite material of the present invention. A sectional    view of this high dielectric constant composite material is shown in    FIG. 17, from which it will be seen that the high dielectric    constant composite material of this embodiment is of a structure in    which an inorganic filler comprising a metal/inorganic matter    composite powder with its surface coated with an insulation layer 2,    said insulation layer being further coated with a surface film 3, is    dispersed in a resin 4.

The dielectric constant, dielectric loss tangent and volume resistivityof this high dielectric constant composite material were determined inthe same way as in Example 1. The results are shown in Table 1.

EXAMPLE 8

A process for producing the high dielectric constant composite materialaccording to the eighth embodiment of the present invention isexplained. In this Example, there were used Epikote 828 (produced byYuka Shell Epoxy Co., Ltd.) as epoxy resin, m-phenylenediamine (producedby Wako Pure Chemical Industries, Ltd.) as epoxy resin curing agent, and2E4MZ-CN (produced by Shikoku Chemicals Corp.) as curing accelerator. Aflat Fe/BaTiO₃ composite powder mixed at the nanometer level was used ashigh dielectric constant material. The average size of the minor axis ofthis composite powder was 0.2 μm, and the Fe to BaTiO₃ volume ratio was7:3. A sectional view of the Fe/BaTiO₃ composite powder used is shown inFIG. 14. A phosphate-based chemical treating solution comprising 0.4mol/l of benzotriazole as rust inhibitor and 0.1% by weight of EF104(produced by Tohchem Products Corp.) as surfactant was used for theinsulation of the Fe/BaTiO₃ composite powder. S510 (produced by ChissoCorp.) was used as the surface treating solution for the insulated ironpowder.

-   (1) To 1 kg of Fe/BaTiO₃ composite powder, 200 ml of the insulation    treatment solution was added and the mixture was stirred by a V    mixer for 30 minutes and then heated at 180° C. for 60 minutes. A    sectional view of the Fe/BaTiO₃ composite powder after the    insulation treatment is shown in FIG. 15.-   (2) The Fe/BaTiO₃ composite powder which had undergone the    insulation treatment of (1) was then subjected to a surface    treatment with an S510 solution diluted to 1 wt % concentration with    a water/methanol mixed solvent, under the conditions of 150° C. and    one hour. A sectional view of the Fe/TaTiO₃ composite powder after    the surface treatment is shown in FIG. 16.-   (3) To a liquid epoxy resin EP828, the Fe/BaTiO₃ composite powder    subjected to the surface treatment of (2) was added in such an    amount as to hold 50% by volume and the mixture was kneaded by a    three-roll mill. To the kneaded mixture, m-phenylenediamine was    added in an amount making it equivalent to the epoxy resin in    relation to the curing reaction, followed by further addition of    2E4MZ-CN in an amount of 0.5 part by weight based on the epoxy resin    and the mixture was kneaded by a three-roll mill.-   (4) The mixture obtained in (3) was heated and cured at 80° C. for 4    hours and then at 180° C. for 4 hours to obtain a high dielectric    constant composite material of the present invention. A sectional    view of this high dielectric constant composite material is shown in    FIG. 17.

The dielectric constant, dielectric loss tangent and volume resistivityof this high dielectric constant composite material were determined inthe same way as in Example 1. The results are shown in Table 1.

The results of Examples 1 to 8 confirm that the substrates made by usingthe high dielectric constant composite material of the present inventioncharacteristically have a high dielectric constant, a low dielectricloss tangent and a high volume resistivity, and thus are possessed ofthe advantageous properties as a substrate having a built-in filter, A/Dconverter, terminals, decoupling condenser, energy storing condenser orsuch.

Comparative Example 1

A process for producing the organic resin/metal composite materialaccording to the first comparative example is explained. In thiscomparative example, there were used EP828 (produced by Yuka Shell EpoxyCo., Ltd.) as epoxy resin, m-phenylenediamine (produced by Wako PureChemical Industries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN(produced by Shikoku Chemicals Corp.) as curing accelerator. Iron powderhaving an average particle size of 5 μm was used as a starting materialfor organic resin/mineral constant material. For the insulation of ironpowder, a phosphate-based chemical treating solution containing 0.4mol/l of benzotriazole as rust inhibitor and 0.1% by weight of EF104(produced by Tohchem Products Corp.) as surfactant was used. S510(produced by Chisso Corp.) was used as surface treating solution foriron powder after the insulation treatment.

-   (1) To 1 kg of iron powder having an average particle size of 5 μm,    200 ml of the insulating treatment solution was added and the    mixture was stirred by a V mixer for 30 minutes and then heated at    180° C. for 60 minutes.-   (2) The iron powder which had undergone the insulation treatment    of (1) was then subjected to a surface treatment with an S510    solution diluted to 1 wt % concentration with a water/methanol mixed    solvent, under the conditions of 150° C. and one hour.-   (3) To a liquid epoxy resin EP828, the iron powder subjected to the    surface treatment of (2) was added in such an amount as to hold 50%    by volume and the mixture was kneaded by a three-roll mill. To the    kneaded mixture, m-phenylenediamine was added in an amount making it    equivalent to the epoxy resin in relation to the curing reaction,    followed by further addition of 2E4MZ-CN in an amount of 0.5 part by    weight based on the epoxy resin and the mixture was kneaded by a    three-roll mill.-   (4) The mixture obtained in (3) was heated and cured at 80° C. for 4    hours and then at 180° C. for 4 hours to obtain an organic    resin/metal composite material.

The dielectric constant, dielectric loss and volume resistivity of theobtained organic resin/metal composite material were determined in thesame way as in Example 1. The results are shown in Table 1.

The results show that although this organic resin/metal compositematerial has a satisfactory dielectric constant and volume resistivity,it suffers an intolerably high dielectric loss tangent and is unsuitedfor use as a substrate material.

Comparative Example 2

A process for producing the organic resin/metal composite materialaccording to the second comparative example is explained. In this secondcomparative example, EP1001 (produced by Yuka Shell Epoxy Co., Ltd.) wasused as epoxy resin, dicyandiamide (produced by Wako Pure ChemicalIndustries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN (produced byShikoku Chemicals Corp.) as curing accelerator. Zinc powder having anaverage particle size of 0.5 μm was used as a starting material for theorganic resin/metal composite material. S510 (produced by Chisso Corp.)was used as surface treating solution for zinc powder.

-   (1) The zinc powder was surface treated using an S510 solution    diluted to 1% by weight with a water/ethanol mixed solvent, under    the conditions of 150° C. and one hour.-   (2) An epoxy resin EP1001 was dissolved in methyl ethyl ketone to a    concentration of 70% by weight.-   (3) To the methyl ethyl ketone solution of epoxy resin EP1001    prepared in (2), the zinc powder subjected to the surface treatment    of (2) was added in such an amount that it would hold 50% by volume    after curing of the resin, and the mixture was kneaded by a    three-roll mill. To this mixture, dicyandiamide was added in an    amount of 2.5 parts by weight per 100 parts by weight of epoxy    resin, followed by further addition of Curesol CN in an amount of    0.1 part by weight per 100 parts by weight of epoxy resin, and the    mixture was kneaded by a three-roll mill.-   (4) The resulting mixture was desolvated at 100° C. and then heated    and cured at 180° C. for 90 minutes to produce an organic    resin/metal composite material of the present comparative example.

The dielectric constant, dielectric loss and volume resistivity of thisorganic resin/metal composite material were determined in the same wayas in Example 1. The results are shown in Table 1.

The results show that although this organic resin/metal compositematerial has a satisfactory dielectric constant, it suffers a highdielectric loss tangent and also exhibits a large volume resistivity, sothat it is unsuited for use as a substrate material.

Comparative Example 3

A process for producing the organic resin/metal composite materialaccording to the third comparative example is explained below. In thisComparative Example, EP806 (produced by Yuka Shell Epoxy Co., Ltd.) wasused as epoxy resin, m-phenylenediamine (produced by Wako Pure ChemicalIndustries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN (produced byShikoku Chemicals Corp.) as curing accelerator. A zinc powder having anaverage particle size of 20 μm was used as a starting material for theorganic resin/metal composite material. For the insulation of the zincpowder, a phosphate-based chemical treating solution containing 0.4mol/l. of benzotriazole as rust inhibitor and 0.1% by weight of EF104(produced by Tohchem Products Corp.) as a surfactant was used. S510(produced by Chisso Corp.) was used as a surface treating solution forthe insulated zinc powder.

-   (1) To 1 kg of zinc powder having an average particle size of 20 μm,    200 ml of the insulating treatment solution was added and the    mixture was stirred by a V mixer for 30 minutes, followed by heat    treatment at 180° C. for 60 minutes.-   (2) The zinc powder undergone the insulation treatment in above (1)    was then subjected to a surface treatment using an S510 solution    diluted to 1 wt % concentration with a water/methanol mixed solvent    under the conditions of 150° C. for 1 hour.-   (3) The zinc powder subjected to the surface treatment in above (2)    was added to the liquid epoxy resin EP806 in an amount so as to make    the metal powder 50% by volume, followed by kneading by a three-roll    mill. To the resulting mixture, m-phenylenediamine was added in an    amount equivalent weight to the epoxy resin in relation to the    curing reaction, followed by further addition of 2E4MZ-CN in an    amount of 0.5 part by weight based on 100 parts by weight of the    epoxy resin. The resulting mixture was kneaded by a three-roll mill.-   (4) The mixture obtained in above (3) was heated and cured at 80° C.    for 4 hours and at 180° C. for 4 hours to obtain the organic    resin/metal composite material of this Comparative Example.

The dielectric constant, dielectric loss tangent and volume resistivityof the organic resin/metal composite material of this ComparativeExample were measured in the same manner as in Example 1. The resultsare shown in Table 1.

The results show that this organic resin/metal composite material hasgood value as to the volume resistivity, but has a small dielectricconstant and a large dielectric loss tangent. Thus, this compositematerial is not suitable as a high dielectric constant substratematerial.

Comparative Example 4

A process for producing the organic resin/metal composite materialaccording to the fourth comparative example is explained below. In thisComparative Example, EP1001 (produced by Yuka Shell Epoxy Co., Ltd.) wasused as epoxy resin, dicyandiamide (produced by Wako Pure ChemicalIndustries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN (produced byShikoku Chemicals Corp.) as curing accelerator. A zinc powder having anaverage particle size of 0.1 μm ground by using a ball mill was used asa starting material for the organic resin/metal composite material.Since the zinc powder was agglomerated, it was sieved with a sievehaving an opening of 5 μm so as to pass the agglomerated zinc powderhaving a maximum particle size of 5 μm or less. For the insulation ofthe zinc powder, a phosphate-based chemical treating solution containing0.4 mol/l. of benzotriazole as rust inhibitor and 0.1% by weight ofEF104 (produced by Tohchem Products Corp.) as a surfactant was used.S510 (produced by Chisso Corp.) was used as a surface treating solutionfor the insulated zinc powder.

-   (1) To 1 kg of agglomerated zinc powder having a maximum particle    size of 50 μm, 200 ml of the insulating treatment solution was added    and the mixture was stirred by a V mixer for 30 minutes, followed by    heat treatment at 180° C. for 60 minutes.-   (2) The agglomerated zinc powder undergone the insulation treatment    in above (1) was then subjected to a surface treatment using an S510    solution diluted to 1 wt % concentration with a water/methanol mixed    solvent under the conditions of 150° C. for 1 hour.-   (3) Epoxy resin EP 1001 was dissolved with methyl ethyl ketone as so    to make the concentration 70% by weight.-   (4) The agglomerated zinc powder subjected to the surface treatment    in above (2) was added to the epoxy resin EP1001 dissolved in methyl    ethyl ketone in above (3) in an amount so as to make the metal    powder 50% by volume after resin curing, followed by kneading by a    three-roll mill. To the resulting mixture, dicyandiamide was added    in an amount of 2.5 parts by weight per 100 parts by weight of the    epoxy resin, followed by further addition of Curesol CN in an amount    of 0.1 part by weight per 100 parts by weight of the epoxy resin.    The resulting mixture was kneaded by a three-roll mill.-   (5) The mixture obtained in above (4) was subjected to removal of    the solvent at 100° C., and heated and cured at 180° C. for 90    minutes to obtain the organic resin/metal composite material of this    Comparative Example.

The dielectric constant, dielectric loss tangent and volume resistivityof the organic resin/metal composite material of this ComparativeExample were measured in the same manner as in Example 1. The resultsare shown in Table 1.

The results show that this organic resin/metal composite material hasgood value as to the volume resistivity, but has a small dielectricconstant and a large dielectric loss tangent. Thus, this compositematerial is not suitable as a high dielectric constant substratematerial.

Comparative Example 5

A process for producing the organic resin/metal composite materialaccording to the fifth comparative example is explained below. In thisComparative Example, EP806 (produced by Yuka Shell Epoxy Co., Ltd.) wasused as epoxy resin, m-phenylenediamine (produced by Wako Pure ChemicalIndustries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN (produced byShikoku Chemicals Corp.) as curing accelerator. A copper powder havingan average particle size of 1 μm was used as a starting material for theorganic resin/metal composite material. S510 (produced by Chisso Corp.)was used as a surface treating solution for the chromium plated copperpowder.

-   (1) Chromium plating on the surface of copper powder was conducted    by electric plating using a rotating horizontal barrel apparatus.    Average plating layer thickness was 10 nm.-   (2) The chromium plated copper powder obtained in above (1) was    subjected to surface treatment using S510 treating solution with a    concentration of 1% by weight diluted with a water/methanol mixed    solution at 150° C. for 1 hour.-   (3) The metal powder subjected to the surface treatment in above (2)    was added to the liquid epoxy resin EP806 in an amount so as to make    the metal powder 50% by volume, followed by kneading by a three-roll    mill. To the resulting mixture, m-phenylenediamine was added in an    amount equivalent weight to the epoxy resin in relation to the    curing reaction, followed by further addition of 2E4MZ-CN in an    amount of 0.5 part by weight based on 100 parts by weight of the    epoxy resin. The resulting mixture was kneaded by a three-roll mill.-   (4) The mixture obtained in above (3) was heated and cured at 80° C.    for 4 hours and at 180° C. for 4 hours to obtain the organic    resin/metal composite material of this Comparative Example.

The dielectric constant, dielectric loss tangent and volume resistivityof the organic resin/metal composite material of this ComparativeExample were measured in the same manner as in Example 1. The resultsare shown in Table 1.

The results show that this organic resin/metal composite material hasgood value as to the dielectric constant, but has a large dielectricloss tangent and a small volume resistivity. Thus, this compositematerial is not suitable as a substrate material.

Comparative Example 6

A process for producing the organic resin/metal composite materialaccording to the sixth comparative example is explained below. In thisComparative Example, EP806 (produced by Yuka Shell Epoxy Co., Ltd.) wasused as epoxy resin, m-phenylenediamine (produced by Wako Pure ChemicalIndustries, Ltd.) as epoxy resin curing agent, and 2E4MZ-CN (produced byShikoku Chemicals Corp.) as curing accelerator. A chromium powder havingan average particle size of 1 μm and an Al₂O₃ powder having an averageparticle size of 0.1 μm were used as a starting material for the organicresin/metal composite material. For the insulation of the chromiumpowder, a phosphate-based chemical treating solution containing 0.4mol/l. of benzotriazole as rust inhibitor and 0.1% by weight of EF104(produced by Tohchem Products Corp.) as a surfactant was used.

-   (1) To 1 kg of chromium powder having an average particle size of 1    μm, 200 ml of the insulating treatment solution was added and the    mixture was stirred by a V mixer for 30 minutes, followed by heat    treatment at 180° C. for 60 minutes.-   (2) The chromium powder subjected to insulation treatment in    above (1) and Al₂O₃ powder (3:1 by volume ratio) was added to the    liquid epoxy resin EP806 in an amount so as to make the metal powder    60% by volume, followed by kneading by a three-roll mill. To the    resulting mixture, m-phenylenediamine was added in an amount    equivalent weight to the epoxy resin in relation to the curing    reaction, followed by further addition of 2E4MZ-CN in an amount of    0.5 part by weight based on 100 parts by weight of the epoxy resin.    The resulting mixture was kneaded by a three-roll mill. But the    organic resin/metal composite material of this Comparative Example    was not possible to mix uniform.

As a result, it was revealed that the organic resin/metal compositionmaterial of this Comparative Example was not suitable for a highdielectric constant substrate.

Comparative Example 7

A process for producing the organic resin/metal composite materialaccording to the seventh comparative example of the present invention isdescribed. In this comparative example, ESCN190-2 (produced by SumitomoChemical Co., Ltd.) was used as epoxy resin, H900 (produced by TohtoKasei Co., Ltd.) as epoxy resin curing agent, and TPP (produced HokkoChemical Co., Ltd.) as curing accelerator. A spherical Fe/Al₂O₃composite powder was used as a starting material for the organicresin/metal composite material. The average size of this compositepowder was 10 μm, and the Fe to Al₂O₃ volume ratio was 7:3. Aphosphate-based chemical treating solution comprising 0.4 mol/l ofbenzotriazole as rust inhibitor and 0.1% by weight of EF104 (produced byTohchem Products Corp.) as surfactant was used for the insulation of theFe/Al₂O₃ composite powder. S510 (produced by Chisso Corp.) was used asthe surface treating solution for the insulated iron powder.

-   (1) To 1 kg of the Fe/Al₂O₃ composite powder, 200 ml of the    insulation treating solution was added, and the mixture was stirred    by a V mixer for 30 minutes and then heated at 180° C. for 60    minutes.-   (2) The Fe/Al₂O₃ composite powder which had gone through the    insulation treatment of (1) was subjected to a surface treatment    using an S510 solution diluted to a concentration of 1% by weight    with a water/ethanol mixed solvent, under the conditions of 150° C.    and one hour.-   (3) An epoxy resin ESCN190-2 and a curing agent H900 were dissolved    in methyl ethyl ketone, each to a concentration of 70% by weight.-   (4) To the methyl ethyl ketone solution of the epoxy resin ESCN190-2    prepared in (3), the Fe/Al₂O₃ composite powder which had undergone    the surface treatment of (2) was added to have a concentration of    50% by volume after curing of the resin, and the mixture was kneaded    by a three-roll mill. To this mixture, H900 was added in an amount    making it equivalent to the epoxy resin in relation to the curing    reaction, followed by further addition of TPP in an amount of 0.4    part by weight per 100 parts by weight of the epoxy resin, and the    mixture was kneaded by a three-roll mill.-   (5) The mixture prepared in (4) was desolvated at 90° C. and then    heated and cured at 180° C. for 6 hours to obtain an organic    resin/metal composite material.

The dielectric constant, dielectric loss and volume resistivity of thisorganic resin/metal composite material were determined in the same wayas in Example 1. The results are shown in Table 1.

The results show that although the organic resin/metal compositematerial of this comparative example is satisfactory in dielectricconstant and volume resistivity, it suffers a high dielectric losstangent and is unsuited for use as a substrate material.

Comparative Example 8

A process for producing an organic resin/metal composite materialaccording to the eighth comparative example is explained. In thiscomparative example, there were used Epikote 828 (produced by Yuka ShellEpoxy Co., Ltd.) as epoxy resin, m-phenylenediamine (produced by WakoPure Chemical Industries, Ltd.) as epoxy resin curing agent, and2E4MZ-CN (produced by Shikoku Chemicals Corp.) as curing accelerator. Aflat Fe/BaTiO₃ composite powder mixed at the nanometer level was used asa starting material for the organic resin/metal composite material. Theaverage size of the minor axis of this composite powder was 0.2 μm, andthe Fe to BaTiO₃ volume ratio was 7:3. S510 (produced by Chisso Corp.)was used as the surface treating solution for the iron powder afterinsulation.

-   (1) The Fe/BaTiO₃ composite powder was subjected to a surface    treatment with an S510 solution diluted to 1 wt % concentration with    a water/methanol mixed solvent, under the conditions of 150° C. and    one hour.-   (2) To a liquid epoxy resin EP828, the Fe/BaTiO₃ composite powder    subjected to the surface treatment of (1) was added in such an    amount as to hold 50% by volume and the mixture was kneaded by a    three-roll mill. To the kneaded mixture, m-phenylenediamine was    added in an amount making it equivalent to the epoxy resin in    relation to the curing reaction, followed by further addition of    2E4MZ-CN in an amount of 0.5 part by weight based on the epoxy resin    and the mixture was kneaded by a three-roll mill.-   (3) The mixture obtained in (2) was heated and cured at 80° C. for 4    hours and then at 180° C. for 4 hours to obtain an organic    resin/metal composite material.

The dielectric constant, dielectric loss tangent and volume resistivityof this organic resin/metal composite material were determined in thesame way as in Example 1. The results are shown in Table 1.

The results show that although the organic resin/metal compositematerial of this comparative example had a satisfactory dielectricconstant, it was high in dielectric loss tangent and low in volumeresistivity, and was therefore unsuited for use as a substrate material.

The high dielectric constant composite material according to the presentinvention comprises an organic resin having filled therein a metalpowder of a submicron size which was subjected to a chemical insulatingtreatment with an inorganic salt and surface treatment in order toimprove compatibility with the organic resin, so that it has adielectric constant of 15 or above and suffers a dielectric loss tangentof only 0.1 or less even in the frequency range of the GHz order.

The substrates using the high dielectric constant composite material ofthe present invention typically have a high dielectric constant anddemonstrate a low dielectric loss tangent and a high volume resistivity,so that they are possessed of the advantageous properties in use as asubstrate having a built-in filter, A/D converter, decoupling condenser,energy storing condenser or such.

It will be further understood by those skilled in the art that theforegoing description has been made on embodiments of the invention andthat various changes and modifications may be made in the inventionwithout departing from the spirit of the invention and the scope of theappended claims.

1. A high dielectric constant composite material having a dielectricconstant of 15 or above in the frequency region of from 100 MHz to 40GHz, comprising: an organic resin and, dispersed therein, an inorganicfiller, wherein the inorganic filler comprises a composite fillercomprising a core metal powder particle having an average particle sizeof 5 μm or less or a core agglomerate of metal powder particles havingan average agglomerate size of 5 μm or less; an insulating film coveringthe core; and a surface treatment film covering the insulating film, thesurface treatment film being chemically bonded to the insulating filmand the organic resin.
 2. A high dielectric constant composite materialaccording to claim 1, wherein the composite material has a dielectricloss tangent in the frequency region of from 100 MHz to 80 GHz of 0.1 orless.
 3. A high dielectric constant composite material according toclaim 1, wherein the core of the composite filler further comprises ametallic covering layer on the surface thereof with a thickness of 1000to 1 nm, wherein the metallic covering layer comprises at least onemetal selected from the group consisting of Cr, Cd, Zn, Mn and Fe.
 4. Ahigh dielectric constant composite material according to claim 1,wherein said insulating layer is provided by chemical treatment using aninorganic salt.
 5. A high dielectric constant composite materialaccording to claim 4, wherein said metal powder is powder of Al, Mn, Si,Mg, Cr, Nb, Ni, Mo, Cu, Fe, W, Zn, Sn, Pb, Ag, Ti, Zr, Ta, Pt, Sb or analloy thereof.
 6. A high dielectric constant composite materialaccording to claim 1, wherein the inorganic filler further comprises ametal oxide mixed with the composite filler.
 7. A high dielectricconstant composite material according to claim 1, wherein said metalpowder is a powder of an element of Group 1B, 2B, 3B, 4B, 5B, 6B, 7B, 8,2A, 3A, 4A or 5A (excluding boron, carbon, nitrogen, phosphorus andarsenic) or an alloy thereof.